Python can be used to read data from a variety of places, including databases and files. Two file types that are often used are .txt and .csv. You can import and export files using built-in Python functionality or Python's CSV library. We’ll go through both options! Show Load Data With Built-In Python FunctionsTo both read from and write to a file, you can use the built-in function File name: the directory path to the file that you want to read or write to. Mode: the mode you want to use for the file. The main options are:
To create a new file called “hello.txt” and write “Hello, world!” to it, use the following code:
You can also use the 2 statement to read a file line by line:
This will print out the input file line by line. The CSV LibraryWhile the Python's official CSV documentation says that the CSV library "allows programmers to say, 'write this data in the format preferred by Excel,' or 'read data from this file which was generated by Excel,' without knowing the precise details of the CSV format used by Excel." When using the CSV library, you also need to use the 5 or 6 methods to read from or write to a file.Read External FilesLet's start with reading external files. Let’s say you have a CSV file named favorite_colors.csv that looks like the following:
The 7 method will take all the text in a CSV, parse it line by line, and convert each row into a list of strings. You can use different delimiters to decide how to break up each row, but the most common one is a comma. The code snippet below reads the CSV file and prints each row.
The output will be the following:
While this approach can be helpful sometimes, it treats the header row the same as any other. A more useful method for reading CSVs while recognizing headers to identify the columns is the 8 method. This method knows the first line is a header and saves the rest of the rows as dictionaries with each key as the column name and the value as the column value.The code below shows how to use the 8 method.
The output for this will be:
Much more useful, right? Write to External FilesTo understand writing to external files, let’s go back to our web scraping example. We’ve already written the code to extract and transform the data from the UK government services and information website. We have all the titles and descriptions saved as lists of strings. Now we can use the 0 and 1 functions to write the data into a CSV file.
And there you have it! Your very own file populated with data scraped from the web. Follow along with the screencast below to go through each line. Print out your variables to help you keep track of what your code does at each line! https://vimeo.com/483572506Now download the code by clicking here and run it on your own in your editor. Take the time to understand what each line does, and feel free to revisit the screencast if needed. You may have noticed that some instructions in this code repeat. Try and separate some of this functionality into functions on your own. Once you’ve given it a go, check out this file to compare how I’ve done it, but there is no right or wrong answer. Level-Up: Create, Read, and Write to FilesTime for some practice! 😁 https://api.next.tech/api/v1/publishable_key/2A9CAA3419124E3E8C3F5AFCE5306292?content_id=0f7a256b-78c6-4586-bce1-ae47896651d2 Level-Up, Bonus Round: Work With CSV FilesHere's a chance to get more comfortable with CSV Files. 😁 https://api.next.tech/api/v1/publishable_key/2A9CAA3419124E3E8C3F5AFCE5306292?content_id=f5158d8b-0360-4159-a7c6-91b223f4f2a1 Let’s Recap!
Awesome! You’ve learned how to web scrape by extracting, transforming, and loading data from the web. Next, we’ll delve into the ethical concerns and challenges with web scraping. 1 2 Create an Wow! We're happy to see that you're enjoying our courses (already 5 pages viewed today)! You can keep checking out our courses by becoming a member of the OpenClassrooms community. It's free! You will also be able to keep track of your course progress, practice on exercises, and chat with other members. Register Sign in 1 2 Create an Only Premium members can download videos from our courses. However, you can watch them online for free. 1 2 Create an Only Premium members can download videos from our courses. However, you can watch them online for free. Extract Data From the Web Using Python Libraries
Teachers Will Alexander Scottish developer, teacher and musician based in Paris. Raye Schiller Raye Schiller is a backend software engineer based in New York City and has an MEng. in Computer Science from Cornell University 🙏💻 How do I import a dataset in Python?Steps to Import a CSV File into Python using Pandas. Step 1: Capture the File Path. Firstly, capture the full path where your CSV file is stored. ... . Step 2: Apply the Python code. ... . Step 3: Run the Code. ... . Optional Step: Select Subset of Columns.. How to load dataset in Python using pandas?Pandas Read CSV. Load the CSV into a DataFrame: import pandas as pd. df = pd.read_csv('data.csv') ... . Print the DataFrame without the to_string() method: import pandas as pd. ... . Check the number of maximum returned rows: import pandas as pd. ... . Increase the maximum number of rows to display the entire DataFrame: import pandas as pd.. How do I import a dataset?Importing data into a dataset. If needed, select your dataset from list on the Datasets page to open its Import tab.. Choose the import source for your data: BigQuery, Cloud Storage, or your local computer. Provide the information required. ... . Click Import to start the import process.. How do you use dataset in Python?Using Pandas and Python to Explore Your Dataset. Setting Up Your Environment.. Using the Pandas Python Library.. Getting to Know Your Data. Displaying Data Types. ... . Getting to Know Pandas' Data Structures. ... . Accessing Series Elements. ... . Accessing DataFrame Elements. ... . Querying Your Dataset.. Grouping and Aggregating Your Data.. |